Help - Very high Alk low pH, and low Ca

[NewfiDog]

You may want to double check your mag. My red sea mag kit always reads 1600, no matter what i test it on. I compared it with fresh batch of water and tank water always 1600. I used an elos kit and the fresh batch was exactly what the label reads , my tank was around 1150.

 

[Boomer]

Robin

You need to stop playing with your system it is a mess and getting worse.

1. Shut off the Ca reactor and make sure it is 100% off and nothing is leaking into the tank

2. Stop all dosing.

3. Do two 50% or greater WC, one on day one an one on day two.

4. Who's salt are you using ? There is no sense in using a salt that is high in Ca++, Mg++ and Alk, as it is self defeating to fix your problems.

4. Once all is well and with in normal NSW range, Ca++ 410-420 or so, Mg++ 1300 - 1350 or so and dKH like 6-9 then turn the Ca reactor back on with NO ! CO2 and let it run for a day or two and recheck parameters. Then start to barely turn on the CO2 for reactor, where the reactor of pH ~7 for starts.

 

[cybermeez]

You may want to double check your mag. My red sea mag kit always reads 1600, no matter what i test it on. I compared it with fresh batch of water and tank water always 1600. I used an elos kit and the fresh batch was exactly what the label reads , my tank was around 1150.

$#@%& test kits! I have a Sera kit (still within the "best before" date) that I was using which gave me the result of 1300 on Monday. I'll check it again with that tonight and shut off the calcium reactor etc.

 

[cybermeez]

Robin

You need to stop playing with your system it is a mess and getting worse.

1. Shut off the Ca reactor and make sure it is 100% off and nothing is leaking into the tank

2. Stop all dosing.

3. Do two 50% or greater WC, one on day one an one on day two.

4. Who's salt are you using ? There is no sense in using a salt that is high in Ca++, Mg++ and Alk, as it is self defeating to fix your problems.

4. Once all is well and with in normal NSW range, Ca++ 410-420 or so, Mg++ 1300 - 1350 or so and dKH like 6-9 then turn the Ca reactor back on with NO ! CO2 and let it run for a day or two and recheck parameters. Then start to barely turn on the CO2 for reactor, where the reactor of pH ~7 for starts.

I'm using Reef Crystals for salt. If what NewfiDog says about the Red Sea Mg test kit turns out to be true, things are going to be a little bit better with the Mg in a more normal range. I'll get some Elos kits tonight on the way home from work. I want to get to the bottom of what all the numbers really are.

To think, all this started with a bad pH probe.

 

[Boomer]

OK, I'll wait but right now IO is a better idea.

 

[cybermeez]

OK, I'll wait but right now IO is a better idea.

I'll pick some IO up too. Certainly can't hurt. Can I wait for my R/O unit to produce enough R/O water or is this so urgent that I should use ((shudder)) conditioned tap water?

 

[cowfish]

I may have missed this before but... have you tested the dissolved oxygen in the water. Low O2 could account for the slightly low pH and would not affect the corals.

Be careful with the alkalinity. Sudden changes in alk are worse than high or low alk. A large sudden shift either way will have a deleterious effect on SPS - bleaching, tissue recession, etc.

 

[Awibrandy]

Something is not right--I find it nearly impossible ( totally impossible?) that you have low pH with you Alk. that high.

Not sure why you state the above Randy.
I have been having a similar problem with my reef. Alk through the roof at the same #s as Robins, and low PH.

Robin wishing you & me the best out come as possible. I did loose all my sps, and some lps. But I am coming back slowly, as of yesterday my alk was at 13dkh. I have been doing w/c every other day, and dosing just cal & mag.

 

[prattreef]

Because Alkalinity is the measure of the buffering capacity against drops in pH.

 

[cybermeez]

Picked up two Elos test kits tonight - Mg and Ca. They were out of Alk so I continued to use the Red Sea Alk kit I have and the API pH kit I've been using. I tested tonight and got the following readings:

pH=8.4 (API kit)
Alk=13.2 (Red Sea kit)
Ca=400 (Elos kit)
Mg=1500 (Elos kit)

I'm fairly confident that these numbers are accurate, or at least close. I haven't dosed any supliments and this morning had already dialed back the calcium reactor. With these latest numbers, what are your thoughts Boomer?

 

[rrudo74901]

You are falling back in line.

Ph is good, calc is in low range Alk and mag high range.

Let the tank settle, test everyday for three days and watch what is consumed and how much each day.

 

[rrudo74901]

Any update on your levels?

 

[Boomer]

Because Alkalinity is the measure of the buffering capacity against drops in pH.

Nope against drops due the addition of a acid. You can have all the Alk you want and when CO2 enters the pH will drop, no matter what the Alk is. Take a glass of water with a pH meter in it and bump the Alk to like 15 dKH, blow in it with a straw and watch the pH crash. Re-measure the Alk and it will still be 15 dKH. It is cooler to watch with a pH indicator in the glass as you can watch the color change. A common limnological term for Alk is ANC, Acid Neutralizing Capacity. Technically speaking, Buffer Captivity is not the same thing as Alk, as BC is the ability to stop pH shifts up or down. Alk is a downward shift thing. However, I know it is confusing, but Alk is a indication measurement of BC. So, it is Ok to use that term. BC In seawater is almost solely controlled by CO2.

BC

Buffer capacity, ?, is a quantitative measure of the resistance of a buffer solution to pH change on addition of hydroxide ions. It can be defined as follows.

where dn is an infinitesimal amount of added base and d(p[H+]) is the resulting infinitesimal change in the cologarithm of the hydrogen ion concentration.

With this definition the buffer capacity of a weak acid, with a dissociation constant Ka, can be expressed as

where CA is the analytical concentration of the acid. pH is approximately equal to -log10[H+]


So, the higher the Alk the higher the BC. In short it means meq/L/pH unit shift. In NSW the max BC is at a pH of ~ 6 and ~9 , as half is a acid and half is a base. Diagram below. And if Salinity or temp change this changes. In FW this graph is off to the right.

Low O2 could account for the slightly low pH

O2 has no effect on pH. It is CO2

I'll now go back to my cave

 

[rrudo74901]

I'll delve into the above post more tomorrow and absorb it, but is there a mathematical relationship between Alk, mag and calc? If I understand the relationship between these three elements correctly, the mag is the bridge between the Alk and calc being "balanced". Or the higher the mag concentration, the more ability of the water to "hold" onto more calc at a higher Alk without precipitation. Is this somewhat correct?

 

[Boomer]

but is there a mathematical relationship between Alk, mag and calc?

Yes, there is, called Omega numbers.

 

[cybermeez]

I'll post new numbers tonight. But in the meantime, since I last posted I've changed a total equivalent of half the tank's water and used IO salt instead of RC. I've also got a new pH probe for the controller on the way thanks to the lovely gift certificate in the goody bag given to attendees of the recent frag swap.

 

[tomtoothdoc]

it's been almost a month. any update?